Shunt compensators are used in high voltage networks to compensate for excessive reactive power consumption or generation. Thyristors are often used to allow control of the exchanged reactive power of such shunt compensators on a per cycle basis.
A conventional way of connecting shunt compensators can be seen in FIG. 1. An interfacing transformer 101 is used between the transmission grid 102 and the thyristor controlled/switched reactive power elements, to adapt the rated high voltage of the transmission system to a lower voltage in the range 10-30 kV to which Thyristor Controlled Reactors (TCR) 103, Thyristor Switched Reactors (TSR) 103 and/or Thyristor Switched Capacitors (TSC) 104 are connected. Typically also shunt banks and/or harmonic filters 105 will be connected to the same low-voltage bus.
However, the connection of the prior art exhibits some drawbacks with respect to performance, such as transformer saturation at high capacitive delivery or at high grid voltage, reactive power consumption in the transformer and excessive rated secondary currents and very high short-circuit currents.
Consequently, there is a need to improve the use of shunt compensators in view of the prior art.